Way back in the early days of computer connectivity, circa early ’80s, IP version 4 rolled out, and the good computer scientists of the time prepared for enough numbers, when combined in multiple variations, to cover plenty of devices — 4.2 billion devices, in fact.

Ha! Silly old computer people! That number is small potatoes these days. To cover the growing need for IP addresses, a new version is rolling out — IPv6. This time, it’s combining letters and numbers, allowing for 340,282,366,920,938,463,463,374,607,431,770,000,000 possible permutations over time.

The only problem: Some IPv4 connections won’t be able to see IPv6 connections without help.

Cause for panic? No. The Post’s Hayley Tsukayama says the switch to IPv6 will be about as cataclysmic as Y2K and May 21’s Rapture-That-Wasn’t.

If you’re still worried, you can check this “eye test” out to see if your computer is prepared for the switch. If you haven’t noticed anything screwy on the Internet (aside from the continued Weiner debate), then you’re probably fine. Google, Facebook, Yahoo! and the State, Commerce and Veterans Affairs departments are all using IPv6 addresses today to test the settings. Hence the wild IPv6 day celebrations. Okay, maybe not wild. Or any actual celebrations. But someone did write a song: